Controller.



R. H. McLAlN.

CONTROLLER. 7 APPLICATION FILED SEPT, 18, 1916- 1 ,247,436. I PatentedNov. 20, 1917.

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UNITED STATES PATENT oruucn.

ROBERT H. MOLAIN, OF SCHENECTADY, NEW YORK, ASSIGNOR T0 GENERAL ELECTRICCOMPANY, .A. CORPORATION OF NEW YORK.

CONTROLLER.

Specification of Letters Patent.

Application filed September 18, 1916. Serial No. 120,687.

To all whom it may concern:

Be it known that 1, ROBERT H. MGLAIN,

object the provision of improved means whereby the master switch whichis ordinarily provided for controlling these circuits may be madeconsiderably smaller, lighter and less expensive than those heretoforeused.

My invention relates more specifically to devices having a plurality ofcontacts which successively control a circuit or circuits, such forinstance as acontroller which is commonly used for controlling anelectric motor. Such controllers, ordinarily called drum controllersemploy a rotatable cylinder having a plurality of contact segments whichengage corresponding stationary contact fingers to which the circuits tobe controlled are connected. In the operation of controllers of thischaracter especially where the circuit to be broken is of a highlyinductive character, dangerous arcing may occur at the circuitinterrupting contacts. This is true for instance in the case of a masterswitch or controller which controls separate electro-magneticallyactuated switches. This arcing has necessitated the use of acomparatively large controller in which the spacing between thesuccessive steps of the controller and the spacing between the variouscircuit interrupting contacts are sufliciently large to take care of thedanger of the are at one of the circuit inter rupting contacts beingdeflected over to the adjacent contacts and thus causing a shortcircuitwithin the controller itself, and also to make sure that the controlledcircuits will be positively denergized. Furthermore, because of theheating effect of the arcs, the contact segments and fingers had to bemade comparatively large to provide suflicient cooling surface. Thefriction caused by the controller fingers riding up and down over theedges of the contact segments produced a further heating efiect whichhad to be provided for by constructing these parts larger than wouldotherwise have been necessary. Ofcourse, controllers have beenconstructed with large spacing between the successive operativepositions and between the circuit making contacts and have been providedwith blow out coils, are deflecting plates of insulating materialbetween the contact segments and the like in attempts to obviate thedifiiculties and dangers above pointed out but these have all involvedcomplications which have been expensive to construct and'maintai'n andhave also added considerably to the weight and size of the controller.

One of the objects of my invention is to make possible the use of asmall, light and inexpensive controller in which the spacing between thesuccessive positions of the controller and the spacing between thevarious contacts are materially less than has heretofore been considerednecessary. I accomplish this object by quickly deenergizing thecontrolled circuits and practically eliminating the dangerous arcing attheiircuit interrupting contacts and minimizing the friction and wear ofthe parts.

To accomplish this object I connect a circuit having capacity to eachcoil circuit so as to suppress by absorption the are at the circuitinterrupting contacts and promptly deenergize the controlled circuits.More specifically I connect a circuit having capacity in series witheach coil circuit and across the circuit interrupting gap as thecontroller is moved to successively denergize the coil circuits. Thecircuit having capacity act-s to quickly check the flow of current inthe corresponding coil circuit and simultaneously suppress by absorptionany are which may tend to be formed'at the circuit interrupting gap.More specifically, my invention provides a plurality of condensers, onefor each coil circuit, arranged to check the flow of current in the coilcircuits quickly, thus causing the controlled switches to open veryquickly and suppress the arcs at the circuit interrupting contacts. Thecondensers may be placed either in the controller itself or be separatetherefrom as desired. In one form of my device I provide, in combinationwith the above men tioned features, a controller having segments ofinsulation concentric with and having the same radius as the circuitmaking segments so that the controller fingers slide directly from thecircuit making segments Patented Nov. 20, 1917K to the insulationwithout sliding up or down over the edges of the segments, thusminimizing the wear on the segments and fingers and at the same timeavoiding the dangerous arcing by reason of the action of the circuitshaving capacity.

Referring to the drawings which show one embodiment of my invention,Figure 1 shows a system of control for an electric motor and Fig. 2 is asimplified end view of a part of a controller cylinder having a segmentof insulation flush with the circuit making contact segment and showingthe cooperating contact finger which is adapted to ride over thesesegments. Referring to Fig. 1, the motor 1 is connected to the supplycircuit 2 by means of a trolley pole 3 and is connected to ground bymeans of the electromagnetically actuated switch member 4. Theelectromagnetically actuated switch member 5 is adapted to short circuitthe armature controlling resistance 6, and the electromagneticallyactuated switch member 7 is adapted to short circuit the armaturecontrolling resistances 6 and 8. The highly inductive actuating coils ofthese switches are controlled by means of a master switch or controller9 having two sets of relatlvely movable cooperating contacts. The sizeof these contacts, their spacing from on another and the spacing betweenthe successive operatlve positions of the controller are allcomparatively quite small. Associated with the controller are aplurality of circuits having capacity, the circuits having therein thecondensers 10, 11 and 12. One side of each condenser is connected to itscorresponding coil circuit and the other side is connected to thecontact segments of controller 9. These condensers are adapted to checkvery quickly the flow of current in the swltch coils and suppress anyarcs which may tend to be formed at the master controller segments asthe master controller is moved to deenergize the electromagnets.Referring to Fig. 2 the circuit making segment 13 and the segment ofinsulation 14 are secured to the shaft 15 of the master controller 9.The segment of insulating material 14 is flush with, closely adjoins,and has the same radius as the circuit making segment 13, so that whenthe controller is rotated so as to break the circuit between thestationary contact finger 16 and the circuit making contact 13, thefinger 16 will ride directly from the contact segment onto the segmentof insulation 14, and when the controller is rotated so as to make thecircuit, the finger rides directly from the segment of insulation to thecontact segment, thus reducing to a minimum the wear on the edge of thecircuit making segment 13 and the contact finger 16.

The operation of my device is as follows:

In order to complete the circuit of the motor 1 through the resistance 6and 8 to ground, the master controller 9 is moved through the position ato the position I), when the coil 17 is energized causing the switchmember 4 to close and complete the motor circuit. The circuit for thecoil 17 is from the supply circuit 2, conductor 18, segment 19, throughthe coil to ground. Moving the controller to the position 0 energizcsthe coil 20, and by moving the controller to the position d the coil 21is energ1zed, causing the switch members 5 and 7, respectively to closeand short circuit the resistance 6 and 8 in the motor circuit. Thecontact fingers ride directly from thesections of insulation to thecontact segments w1th a very small amount of friction and wear.

To lower the speed of the motor, the controller is first moved backwardto the position 0 when the controller finger rides off of the segment 18onto the segment 14 of insulation with a small amount of friction. Whenthis happens the condenser 10 is included in the circuit of coil 21 andacross the interrupting gap between the contact making segment 13 andthe controller finger 16. The condenser 10 quickly checks the current inthe coil circuit causing the switch member 7 to bequickly openedremoving the short circuit from the section of resistance 8. Thecondenser 10 connected across the insulation separating the contactsegment 13 and the contact finger 16 suppresses any are which may tendto be formed across this in terrupting gap. When the controller is movedto the position b the condenser 11 is included in the circuit of coil 20and across the interrupting gap between the contact segment and finger,and when the controller is moved to the position a the condenser 12 iconnected in series with the coil 17 and across the correspondinginterrupting gap, the action of the condensers 11 and 12 with respect tothe coils 20 and 17 being the same as that of condenser 10.

By reason of the insulating material flush with and closely adjoiningthe movable segment and the action of these condensers in promptlysuppressing the arcs at the circuit interrupting contacts andeliminating the danger of an arc flashing over from any one of thecontact segments to the adjacent segments, it has been possible to use amaster switch in which the spacing between the successive operativepositions a, b, a, d, and the spacing between the segments themselvesand the sizes of all the parts of the controller are comparatively quitesmall in proportion to the circuits controlled. This master switch orcontroller, may therefore be made considerably smaller, lighter, andless expensive to manufacture and maintain and its life in serviceconsiderably lengthened.

In accordance with the provisions of the patent statutes, I havedescribed the principle of operation of my invention, together with theapparatus which I now consider to represent the best embodiment thereof;but I desire to have it understood that the apparatus shown is onlyillustrative, and that the invention can be carried out by other means.

\Vhat I claim as new and desire to secure by Letters Patent of theUnited States, is

1. Controlling means for electric circuits comprising a master switchhaving a plurality of circuit interrupting contacts closely spaced andhaving a plurality of operative positions in close proximity to oneanother, and means for increasing the safe capacity of the switchcomprising a circuit having capacity connected to each of said circuitsand across the corresponding interrupting gap at the master switch.

Controlling means for electric circuits comprising a master switchhaving a plurality of closely spaced relatively movable cooperatingcircuit interrupting contacts and having a plurality of operativepositions in close proximity to one another, and means for increasingthe safe capacity of the switch and for quickly de'cnergizing thecontrolled circuits, comprising a plurality of condensers connected tothe master switch across the interrupting gaps.

3. Controlling means for an electric motor comprising a plurality ofelectromagnetically actuated switches, a controller therefor having aplurality of closely spaced relatively movable cooperating contacts andhaving a plurality of operative positions in close proximity to oneanother, and means for increasing the safe capacity of the controllercomprising a condenser connected to comprising a plurality ofelectromagnetically actuated switches, a master switch for controllingthe same having a plurality of stationary contacts to which the coilcircuits of said electromagnetically actuated switches are connected anda plurality of movable cooperating contactsfor making and breaking thecoil circuits of said switches, insulating material flush with andclosely adjoining the said movable contacts, and a plurality ofcondensers each of which is connected to a stationary contact and to themovable contacts so as to be included in the respective coil circuit andacross the insulation between the stationary and movable contacts whenthese contacts are separated. a

In witness whereof, I have hereunto set my hand this 16th day ofSeptember, 1916.

ROBERT H. MoLAIN.

